Method of manufacturing a cylindrical magnetic orienting device



Oct. 20, 1964 J. B. SHORE 3,153,277

METHOD OF MANUFACTURING A CYLINDRICAL MAGNETIC ORIENTING DEVICE Filed April 21, 1960 2 Sheets-Sheet 1 dame; .15. J/70/e INVENTOR.

ATTORNEY .1. B. SHORE 3,153,277

ING A CYLINDRICAL MAG C ORIENTI Oct. 20, 1964 NG DEVICE NETI METHOD OF MANUFACTUR Filed April 21, 1960 2 Sheets-Sheet 2 (/0/7791 #5. J/7a/e INVENTOR.

United States Patent 3,153,277 METHOD OF MANUFACTG A CYLlNDRlCAL MAGNETIC ORKENTING DEVlCE James B. Shore, Houston, Tex., assignor to Schlumberger Well Surveying Corporation, Houston, Tex., a corporation of Texas Filed Apr. 21, 1960, Ser. No. 23,825 2 Claims. (Cl. 29-15559) This invention relates to orienting apparatus and its manufacture and, more particularly, to apparatus requiring passage through a small diameter string of tubing for orienting perforating apparatus in a preselected manner within a cased well bore and methods for manufacturing such apparatus.

Recent developments in perforating have been directed towards controlled perforating techniques wherein the perforating apparatus may be accurately located in a section of the well and oriented so that the shaped charges will give an optimum performance by providing proper clearance. One of the inherent difficulties and drawbacks presented by this type of perforation is a need for orienting means which is reliable and sufficiently rugged to withstand the shocks encountered in a perforating operation and yet may be reliably retrieved from the borehole.

Accordingly, an object of the present invention is to provide new and improved orienting means for perforating apparatus which is adapted to pass through a small diameter tubing and accurately locate the perforating apparatus in a large diameter string of casing.

In accordance with the present invention, an orienting device coupled to a perforating apparatus provides a resultant force of magnetic attraction to position the perforating apparatus in a preselected position in a cased wellbore. The magnetic orienting device includes magnets having an outer, cylindrical configuration substantially the same as the configuration of the perforating apparatus and having short, curved pole pieces so as to grip a cylindrical surface. A supporting member connects upper and lower support heads between which the magnets are disposed in a solid and rigid connection thereby preventing undesirable loss of the device in the hole. Portions of the magnets remote from their pole pieces are shielded to minimize any possible force of magnetic attraction other than in the direction of the resultant force.

FIG. 1 illustrates a typical well setup where the present invention may be employed;

FIG. 2 is a view in cross section of one embodiment of the present invention;

FIG. 3 is a view taken along line 33 of FIG. 2;

FIG. 4 is a view in cross section of another embodiment of the present invention;

FIG. 5 is a view taken along line 55 of FIG. 4; and

FIG. 6 is a view in cross section taken along line 66 of FIG. 4.

Referring now to FIG. 1, a typical well setup wherein the present invention may be employed involves a string of casing 10 of ferromagnetic material which is conventionally secured within a borehole (not shown) in a customary manner and traverses earth formations (not shown). A production tubing 11 having a diameter of, say, 2" is shown disposed in the casing 10 and suitably packed off by packing means 12 in a conventional manner so that formation fluid may be produced through the tubing in the customary manner.

Apparatus 13 embodying the present invention, in-

3,153,277 Patented Get. 20, 1964 ice,

a substantially uniform, cylindrical configuration with, of course, a diameter small enough to permit passage through the small diameter tubing 11. As will hereinafter become more apparnt, the magnetic orienting device 14 is adapted to produce a directional force of magnetic attraction or flux density bisecting an axis extending parallel to the central axis of the assembly. By orienting the force of the magnetic attraction with respect to the directions of firing of the perforator, the assembly can be magnetically latched to the casing so that the directions of firing are oriented relative to the casing.

Referring now to FIGS. 2 and 3, the magnetic orienting device 14 includes upper and lower cylindrical support heads 19 and 29 which are coupled together by a supporting rod member 21 and permanent magnets 27 are disposed intermediate of the heads. The upper head 19 has an upper socket end 22 which is arranged for coupling to the connector head 15, which, for example, may include a casing collar locator of the type illustrated in the Fagan Patent No. 2,558,427. The depending lower head 20 has a cylindrical projection 23 of reduced diameter which is sized or arranged to be received in the tubular end of the perforating apparatus 16 and suitably attached thereto, for example, by screws 24. Rod member 21 is preferably of non-magnetic material and has a passageway therethrough so that wires or the like for energizing the perforator can be easily passed through the assembly.

The arrangement of the magnets 27 may best be understood by a consideration of methods of construction of the orienting device 14. Thus, one end of the supporting rod member 21 is suitably threaded into the upper head member 19 and silver soldered thereto. Magnets 27 are formed from horseshoe-shaped, non-magnetized magnet stock. For use with the present invention, the horseshoe magnets are subjected to a grinding operation to provide magnets 27 with a generally cylindrical outer configuration with a diameter slightly less than the diameter of the cylindrical profile of the entire assembly. The ground magnets 2'7 therefore have an essentially crescent shaped cross-section with tips 28 and 29 of the crescent configuration formed at the airgap of the magnets. The length and diameter of the supporting rod member 21 is sized with respect to the diameter of the opening in the magnets 27 so that a number of magnets may be slidably mounted on the supporting rod member. The number of magnets used in an assembly may vary according to the particular magnetic strength necessary to attach the perforating apparatus 16 to the sidewall of the casing. Of

course, this number of magnets required depends upon the particular weight of the entire assembly, but, in general, the magnets required should permit the assembly to slide readily through the tubing 11 and along the side of the casing 10 and yet firmly mix the assembly to the sidewall of the casing when the motion of the cable 17 is stopped.

After the magnets 27 are mounted on supporting rod member 21, the lower head member 20 is threaded to the lower end of the supporting rod member 21. The length of the supporting rod member 21 between the head members 19 and 20 is related to the total thickness and the number of magnets 27 so that the total length of the assembled magnets is about 1 less than the spacing 'file of the upper and lower connecting heads.

. C9 figuration of the heads 19 and 20. Hence, the tips 28 and 29 of the magnets may be aligned generally on the cylindrical profile of the head members 19 and 20 thereby displacing the rearward portion 30 of the magnets 27 inwardly of the'cylindrical profile.

A sheet of thin, woven fiberglass 31 is then wrapped fully about magnets 2'7 to fill in the rearward portion 39 of the magnets'27 to the diameter of the cylindrical pro- Following this, a bonding material 39, such as an epoxy resin, is impregnated into and through the fiberglass to fill the voids in and around the magnets 27, the resin thereafter being cured so that the magnets 27 are securely fixed in a rigid position by the extremely hard epoxy composition. It

will be appreciated that the fiberglass wrapping extends outwardly of the cylindrical profile of heads 19 and 20 about the tips 28 and 29 of .the magnets 27. Thus, the device is now subjected to a grinding operation to con form the bonding material on the magnetic device to the cylindrical profile of the heads-19 and 20 so that the portion of the epoxy coated fiberglass adjacent the tips 23 and 29 of the magnets 27 is removed while the rear- 'ward portions 30 ofthe magnets remain shielded.

At this time, the assembly of the device'14 is completed and magnetizersl 33, and 34 with short cylindrical faces 35 and 36 are disposed adjacent to the tips of the magnets 27 to magnetize the magnets 27 with like poles on respective sides of the air gap and produce short,

curved pole pieces 37 and 38 along a section of outer surface of the tips (indicated by the crossed lines).

It will be appreciated from the foregoing that the use of fiberglass wrapping 31 increases the ease of forming of the shielding surface but that it is not essential, since -a mold or form would permit casting of only an epoxy bonding material to the cylindrical profile ofthe assembly.

The perforating apparatus 16 may be of the'shapedcharge type wherein shaped charges are disposed within a tubular housing. The phasing (or angular displacement of the firing planes) of the shaped charges may be, for example, 180, so that thecharges are arranged to fire in opposite directionsin the same plane as shown by arrows 16a and 16b in FIG/3. 'With this arrangement it will be readily appreciated'that the resultant force of magnetic attraction may be arranged at an angle of 90 relative to the directions of firing (or bisecting the included angle). Thus,'when the magnetic device 14 latches to the casing, the spacing 'of the charges is always uniform with respect to the casing'andthe' perforating axes are aligned in a preselected manner withrespect to the force of magnetic attraction.

Referring now to FIGS. 4-6, in this embodiment, for use in, say, 2 /2" tubing, the assembly and magnetic device14' may have an increased diameter. Because of the increased diameter permitted, head members 19' and 20'- can be coupled together 'by a crescent shaped,'halfshell connecting member 21' preferably comprised of nonmagnetic material. The connecting member 21' may be suitably coupled to the head members by welding or the like. The interior of member 21' is sufficient to accommodate magnets 27, as above described, which are inserted into the interior of connecting member 21'. A small diameter tube 40 for conductors is silver soldered eccentrically to the heads 19' and 20 and extends through the centers of the magnets 27. An epoxy resin bonding material 39 is then used to secure or pot the magnets 27 in connecting member 21' and with tips 28 and 29 of the magnets facing outwardly from the opening of member 21. Pole pieces 37 and 38 are produced on magnets 27 as described heretofore. Along the axis in which the force of magneticattraction is the greatest, the heads 19' and 2t? are provided with hard metal inserts 42 and 43 such as tungsten carbide which extend a slight distance outwardly of the cylindrical profile of the assembly thereby spacing the assembly slightly away from the wall of the casing to prolong the life of the tool by minimizing Wear on the magnets27.

While particular embodiments of the present invention have been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects, and therefore the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope -of this invention.

What is claimed is:

1. A method of manufacturinga cylindrical magnetic orienting device for use in a cased well bore comprising the steps of: assemblying an upper cylindrical head with a lower cylindrical head by means of an elongated supporting member and including between the upper and lower heads a number of crescent shaped elements of magnetizable materialsstacked loosely one upon the other, each of said elements-having a generally cylindrical outer'surface terminating at spaced-apart circumferential tip portions with a void space between such spaced-apart tip portions, aligning the circumferential tip portions of such elements in longitudinal alignment with one another and maintaining suchalignment *while impregnating such assembly with a bonding material to -fill voidspaces therein and secure such magnets with their circumferential tip portions in fixed longitudinal alignment, and permanently magnetizing the elements to force for attracting such device toward a cased wall ofa produce spaced magnetic poles aligned lengthwise of said device which thereby provides a radial magnetic i the steps of: stacking loosely'oneupon the other a number of crescent-shaped elements of magnetizable mateassembly with a bonding material to fill void spaces therein and secure such elements withtheir circumferential tip portions in 'fixed longitudinal alignment, and permanently magnetizing the elements to produce spaced magnetic poles aligned lengthwise of said device which thereby provides a radial magnetic forcefor attracting said device to'a cased wall of a well bore.

References Cited in the'file of this'patent UNITED STATES PATENTS 1,432,920 Swanson Oct. 24, 1922 2,432,819 Schumacker Dec. 16, 1947 2,683,921 Goss etal July 20, 1954 2,689,007 .Beyer et al. Sept. 14, .1954 2,896,721 Cannaday July 28, 1959 2,915,812 Rettinger Dec. 8, 1959 3,024,392 Baermann Mar. 6, 1962 

1. A METHOD OF MANUFACTURING A CYLINDRICAL MAGNETIC ORIENTING DEVICE FOR USE IN A CASED WELL BORE COMPRISING THE STEPS OF: ASSEMBLYING AN UPPER CYLINDRICAL HEAD WITH A LOWER CYLINDRICAL HEAD BY MEANS OF AN ELONGATED SUPPORTING MEMBER AND INCLUDING BETWEEN THE UPPER AND LOWER HEADS A NUMBER OF CRESCENT SHAPED ELEMENTS OF MAGNETIZABLE MATERIALS STACKED LOOSELY ONE UPON THE OTHER, EACH OF SAID ELEMENTS HAVING A GENERALLY CYLINDRICAL OUTER SURFACE TERMINATING AT SPACED-APART CIRCUMFERENTIAL TIP PORTIONS WITH A VOID SPACE BETWEEN SUCH SPACED-APART TIP PORTIONS, ALIGNING THE CIRCUMFERENTIAL TIP PORTIONS OF SUCH ELEMENTS IN LONGITUDINAL ALIGNMENT WITH ONE ANOTHER AND MAINTAINING SUCH ALIGNMENT WHILE IM- 